Project EULAKES Ref. No. 2CE243P3
European Lakes under Environmental Stressors (Supporting lake governance to
mitigate the impact of climate change)
4.1. Vulnerability Assessment
Deliverable 4.1.1 Joint lake vulnerability and risk assessment methodology Part
B: Lake Balaton
Károly Kutics Gábor Molnár, István Hegedűs Lake Balaton Development
Coordination Agency
1
Contents
Executive summary .................................................................................................................... 3
1.
Introduction ......................................................................................................................... 8
2.
Methodology ........................................................................................................................ 9
2.1. Definition of Stressors ......................................................................................................9
3.
Current impacts of Climate Change on Lake Balaton .................................................. 15
3.1. Situation in Hungary ......................................................................................................15
3.2. Situation in the Lake Balaton region ............................................................................18
4. Vulnerability to the effects of climate change - future scenarios ...................................... 30
4.1. Hydrology and water quantity ......................................................................................30
4.2. Lake water temperature .................................................................................................37
4.3. Water quality ..................................................................................................................38
4.4. Reed belt and peat bogs ..................................................................................................43
4.5. Fish and other macrofauna ............................................................................................45
4.6. Invasive species ...............................................................................................................47
4.7. Land use and agriculture ...............................................................................................50
4.8. Hunting ............................................................................................................................52
4.9. Tourism ...........................................................................................................................52
4.10. Infrastructure ................................................................................................................55
5. Assessment of potential economic impacts ......................................................................... 56
6. Summary of findings related to vulnerability .................................................................... 58
Literature................................................................................................................................... 62
2
Executive summary
Vulnerability is the degree to which a system is likely to experience harm due to exposure to a
hazard. The purpose of vulnerability assessment is to determine the hazards in the form of stresses or
perturbations, sensitivity of the system towards these factors and resilience, i.e. the system's ability to
return to the original/favourable condition on its own accord.
The framework and methodology described in Part A: Lake Neusiedl was largely adopted. Available
information on climate change predictions (various scenarios) has been analyzed and receptors of
climate and other stresses were identified. The receptors are mostly based on the investigations of
WP 6.1.3 but receptors deemed important to Lake Balaton were determinded as well.
According to the meteorological data of the past decades, Lake Balaton watershed is warming,
precipitation is slightly decreasing, and the water balance is showing higher variability. Future
climate predictions invariably show increases in temperature, and reduction of water excess in the
natural water balance (NWB or NWRC). Certain scenarios (Nováky, 2008) predict permanent
negative NWB by as soon as 2050. It should be emphasized that there is a great deal of uncertainty in
predictions on the regional scale. However, one of the most vulnerable receptor is water quantity.
The NWB of Lake Balaton may be improved by water transfer from other watersheds, but this action
would result in other stresses and vulnerabilities, such as water shortage on the other watershed,
introduction of foreign species, conflicts of interests, etc.
Lake water temperature is expected to increase in the order of a few oC. This would benefit tourism,
especially on the beaches and water related sports, resulting in higher income for the tourism sector
and reducing economic vulnerability in the region. However, at the same time, higher temperatures
result in adverse effects, such as less favourable water quality, stress on the ecological system, less
(or disappearance of) ice cover making reed management difficult, and human health problems.
Water quality is very vulnerable due to the extreme shallowness of Lake Balaton. Climate change
would bring unfavourable changes, such as more nutrient release from the sediment and increased
erosion resulting in higher algae levels, increase of dissolved inorganic content due to increased
evaporation and less (or negligible) water exchange.
The reed belts would benefit from more frequent low water level and wide year-to-year level
fluctuations, as it was experienced during the year 2000-2004 drought period. As long as the area of
reed stands grow simultaneously with acceptable water level (i.e. above about 60 to 70 cm), the
3
ecological system benefits from the phenomenon (in case of extremely low water level reed stands
dry up resulting in (at least temporarily) significant loss of aqueous habitat). However, advance of
reed-covered area would have adverse impact on various uses of the lake, such as bathing,
swimming, sail boating, etc.
Fish population is declining and there are several non-indigenous species in the lake with high
population. Prediction of changes in the fish population is difficult, but thermophilic species would
advance with warming. It is expected that one of the problem species, silver carp still will not be able
to spawn in the warmer water.
Warmer and drier summer periods will not favor agricultural production in general. However,
vineyards may benefit from warming due to the reduced damages from frosts and the, possibility to
grow more Mediterranian species.
Tourism may expect favourable changes on the short to mid-term due to higher water and air
temperatures as long as water quality do not deteriorate. This would result in longer tourist seasons
and more visitors engaging in water leisure activities.
Table E1 shows the summary of the results of qualitative vulnerability assessment. Receptors
(indicators) of very high and high vulnerability should be addressed during the development of
measures based on the adaptive capacity at regional and national level.
Table E1. Qualitative Vulnerability Assessment for Lake Balaton (up to ca. 2040)
4
Receptors
Lake water
level
Current
Stresses
Precipitation
deficits
Vulnerability Assessment
Projected Climate
Change Impacts Sensit- Adaptive Capacity
Vulnerivity
Higher frequency of Very
High
drought periods
Flooding
High
Slightly higher
frequency of extreme
events
High
Ice damage to
Slightly higher
shoreline
frequency of extreme
structures
events
Peat
fires
at More frequent peat High
marshlands adjacent fires due to low
water level and dry
to the Lake
conditions
Water
Temperature
temperature
increase
Water quality Occasional
algae
blooms
High
Occasional algae
blooms
More frequent algae High
blooms
Very
Growth of benthic Increase in
filamentous algae frequency and mass High
Cl. glomerata
of Cl. glomerata
Appearance of
algae toxins
Increased frequency Medium
and conc. of algae
toxins
Pathogens
Increased
concentration and
survival rate
Flash floods
Reed belt
Grasslands
Vineyards
Changes in reed
area, damage at
extreme events
Rare drought
damage
Drought damage
ability
Very high
Outflow control,
Water transfer, Water
resources
management at river
basin level
Increase Sió canal and Very high
sluice
discharge
capacity,
Increase Sió canal and Very high
sluice
discharge
capacity
Control water level of High
marshlands
Reduction of external Medium
P load
Reduction of external High
P load, Management
of Kis-Balaton
Reduction of external High
P load, Mechanical
removal from beaches
Reduction of external
P load
Low
High
Urban runoff control
Swan population
control
Medium
Increase of erosion High
and pollutant load
Land management,
Urban runoff control
High
More damage at
extreme events
Low
More frequent
drought damage
More frequent
drought damage,
more pests
Low
5
High
Water level
management, reed
harvesting practices
None
Species selection,
good practices
Low
Low
Low
Receptors
Vu nerability Assessment
Current Projected
Stresses
Climate
Change
Sensitivity
VulnerTable E1. Qualitative Vulnerability Assessment for Lake Balaton (up toAdaptive
ca. 2040)
Impacts
Capacity
ability
(Continued)
Agriculture
in general
Forestry
Invasive
species
Fishery
Tourism
Human
health
Damage due to
extreme events
High
More frequent
drought damage,
heat stress,
erosion, new pests
Damage due to
extreme events, new
pests
Competition with
indigenous species
More frequent
drought damage,
heat stress, pests
More favourable
conditions for
propagation
Human health
More favourable
risks due to
conditions for
allergens
propagation
Occasional drying More
frequent
out of spawning drying
out
of
areas
spawning areas
Reduced
Even less
possibility of eel
possibility of eel
removal at outflow removal
Influence of
extreme weather
Medium
Medium
High
Medium
Medium
High
More frequent
occurrence of low
water levels, heat
days, less ice
cover
Occasional water More
frequent High
quality problem water
quality
problem
Medium
Heat days,
More heat days,
allergens, algae
spread of new
toxins
allergens, higher
level of algae
toxins
6
Species selection,
good practices,
melioration
Medium
Species selection,
understorey
management
Removal and
control efforts
Medium
Removal
campaigns, good
agric. practices
Outflow control,
water transfer
Medium
Outflow control
Medium
Outflow control,
water transfer,
attraction
development, ice
rinks
High
Medium
Medium
Medium
Nutrient load
reduction, algae
removal
Heat
shelters, Medium
allergen
control,
reduction of pollutant
load, rising public
awareness
Receptors
V nerability Assessment
u (up to ca. 2040)
Table E1. Qualitative Vulnerability Assessment for Lake Balaton
Sensitivity
Stresses
Climate
Change
Adaptive
Vulner(Continued)
Impacts
Capacity
ability
Infrastructure
Current
Projected
Increased
More erosion
High
erosion in built-up and pollution from
area due to
built-up area
extreme events
Erosion control
Medium
measures, rain water
storage,
treatment,
reuse
Damage to
buildings due to
ground water level
changes
Odour problem
of sewer
pumping stations
More frequent and High
larger ground
water level
changes
More odor
High
problems due to
higher water
temperature and
less flow
Rain water storage,
recharge, ground
water level control
High
Odour control
measures,
switching drinking
water resources
from Lake to karstic
water
Medium
Problem of
ferry, boat and
marina use due
to low water
level
Damages to
infrastructure
due to extreme
events (winds,
heavy rain, snow
and ice)
Increase of
frequency of
problems
High
More frequent
physical
damages to
infrastructure
and buildings
Medium
Modification of
Medium
ferry ports, dredging
of
marinas, use of
smaller boats
Medium
Development of
disaster plans and
measures
7
1. Introduction
Lake Balaton and its surronding area are relatively well researched and studied region. However,
global changes represent new challenges to this part of Hungary as well. Since the late 1960s the
lake often struggled with algae blooms, but, thank to various water quality control measures and
the radical drop of fertilizer use due to radical land ownership changes (privatisation) in the
1990s, significant improvement was achieved in the last 15 years. The severe drought and
accompanying water level drop between year 2000 and 2004 drew the attention to the fact that
Lake Balaton is a vulnerable system. At the same time, it became obvious that new situations and
questions may emerge that neither scientists nor politicians or citizens are able to give simple and
easy answers on the basis of our present level of knowledge.
Similar situations such as low water level occured in the past several times (not because of
negative natural water balance) but the lake and its neighbourhood was much less sensitive to
such changes since the area's population, infrastructure and role in the national economy was a
small fraction of the present time. In addition, natural environment of Lake Balaton was not, or
was to a very small degree, under other stresses.
Vulnerability of the Lake Balaton region is determined by two main factors. On one hand, how
much the region is burdened in terms of environmental and socio-economic stresses. On the other
hand, how the region is able to cope with the consequences of these stresses. The stresses may be
related to changes both in the environment or the society, such as sewage load or demographic
circumstances. Some of the stresses originate from inside the region, such as the loss of habitat
due to construction, while others originate from outside the region, such as climate change.
The natural, social and economic factors are closely interrelated, that is manifested, e.g. in the
relation between the high quality environment (i.e. not crowded, not polluted, noise free,
attractive and rich in natural values) and high-end tourism (i.e. high spending, long-staying
tourists). At the same time, it should be recognized, that the external factors are also interrelated,
which is clear from the global responses to climate change resulting in radical changes in the use
of fossile energy resources (at least on the long run).
2. Methodology
2.1. Definition of Stressors
Climate change parameters are real and legitimate stressor stressor of Lake Balaton region since
impacts of climate change are already well documented in the region. Lake Balaton shows more
8
severe impacts as compared to the Hungarian average. While the western part of the catchment area
(Zala river subcatchment) used to be the wettest region of the country, decrease in pecipitation was
most significant there. The water balance of Lake Balaton is determined by inflow, direct
precipitation on lake surface and evaporation. The considerable deficiency in precipitation and
inflow between years 2000 and 2003 and the high evaporation resulted in significant level drop
(some 70 cm). Therefore climate change can be identified as one of the the main stressors to the lake
and its environment. Climate change has also strong socio-economic impacts, since the major
economic sector is tourism in the region. Tourism revenues exceeding 1 billion Euro are realized in
the Lake Balaton Priority Resort Area (LBRA) including the lake and 179 municipalities around it.
1.1.1. Climate scenarios
Various climate scenarios are considered in drawing conclusions and assessing
vulnerabilities of Lake Balaton and its region.
-
Climate scenario 2100 (period 2071-2100). This regional climate change scenario was
developed by the AIT Austrian Institute oftechnology within the WP 4.3.2. The
Intergovernmental Panel on Climate Change (IPCC) provides a range of scenarios based on
assumptions of the future development of technologies and society. Out of this the scenario A1B
was selected because it represents a moderate increase of Green House Gases and is located in
the centre of all assumptions (Refer to Part A: Lake Neusiedl for details).
-
Climate scenarios of the EU project PRUDENCE as applied in the Balaton Adaptation Project
(2006 -2009) are used to evaluate water quality (eutrophication) - based on B2 and A2 emission
scenarios
-
Specific scenarios used by researchers to evaluate water balance of Lake balaton (Novaky,
Somlyody and Honti, Thacker).
1.1.1.1. Climate parameters 2100
i. Temperature
9
Figure 1. Mean seasonal temperature for 30 year periods
Figure 2. Change of mean seasonal temperature for 30 year periods as compared to 1971-2000
10
ii. Precipitation
Figure 3. Mean seasonal precipitation in mm/year
Change of Mean Seasonal Total Precipitation Sum - Lake Balaton
%
3
2
E
I
5
:
0
-
i
2
0
-i
1
.! Hi
5
-15
0
-20
-30
jI
CI
1-
„
-10
1
-25
■
1-
n-l
F
l
I j ' f QQI inni
- 1961 1971 iqg
M1
n
->
rr
L
2
0
i
20
3
20 (
20"
L-
-35
-40
E
—
'
:
sprin 1
g
summ
er
S
autumn
-
Figure 4. Change of mean seasonal precipitation for 30 year periods as compared to
1971-2000
11
iii. Drought and Heat
1961/90 1971/00 1931/10 1991/20 2001/30 2011/40 2021/SO 2031/60 2041/70 20S1/80 2061/90 2071/00
Figure 5. Mean of maximum length of heatwaves for 30 year periods
Figure 6. Change of mean of maximum length of heatwaves for 30 year periods as
compared to 1971-2000
12
iv. Extreme Events
30y Mean of Heat Days (> 30°C) per Year - Lake Balaton
days
95
90
8
5
s
o
7
5
7
0
5
5
S
O
5
5
5
0
4
5
4
0
3
5
5
0
2
5
2
0
1
5
j hUyJ yu iuu
11
1961/90 1971/00 19S1/10 1991/20 2001/30 2011/40 2021/50 2031/60 2041/70 2051/80 2061/90 2071/00
Figure 7. Mean of number of heat days for 30 year periods
days
30y Mean of Frost Days (< 0°C) per Year- Lake Balatori
110 1------------------------------------------------------------------------------------------------------------------------------100 ' 90
80 ■■ ----------------------------------- ------------------------- ------------------- —
I I 1 I -----------------------------60 -50 v
I ----- ^m-------- —
—_
1961/90 1971/00 1931/10 1991/20 2001/30 2011/40 2021/50 2031/60 2041/70 2051/80 2061/90 2071/00
Figure 8. Mean of number of frost days for 30 year periods
13
d3y5
30y Mean of Heavy Precipitation Days [> 20 mm/d) per Year - Lake Balaton
1961/90 1971/00 1981/10 1991/20 2001/30 2011/40 2021/50 2031/50 2041/70 2051/80 2061/90 2071/00
Figure 9. Mean of number of heavy precipitation days for 30 year periods 1.2.
Definition of Receptors
Receptors or indicators of change were selected based on the issuesmost relevant to Lake Balaton.
The set of receptors is similar to that of Lake Neusiedl but there are some differences too, reflecting
the difference in importance and utilization of the two lakes. Not only the lake itself, but its
catchment as well as the resort area surrounding it are considered. The receprors include
environmental-ecological and socio-economic receptors as well.
The following receptors were selected:
-
Lake hydrology and water quantity
-
Water quality
-
Water temperature
-
Reed belt and peat bogs
-
Fish and other macrofauna
-
Invasive Species
-
Land use and agriculture
-
Hunting
-
Tourism
-
Infrastructure
This list of receptors is based on the investigations of WP 6.1.3. Within this work package
14
a comprehensive multicriteria assessment matrix was elaborated to describe the influences on the
ecosystem of the lake. Experts of different fields (nature conservation, agriculture, regional
planning, hunting management and science) worked out the criteria for the matrix.
3. Current impacts of Climate Change on Lake Balaton 3.1.
Situation in Hungary
Global climate change is an ongoing process supported by ample monitoring data. The overall
situation in Hungary can be described by Figure 10 to Figure 13. In the last 30 years, annual average
air temperatures changed between +1 and +1.8 oC in various regions of the country. In the Lake
Balaton watershed the change is between +1.2 and +1.5 oC. Precipitation during the last 5 decades
decreased by a few percent in the country overall, but the change is much larger in the Lake Balaton
watershed where some 15 to 25 percent reduction has been experienced.
The long term trend of the annual average temperature increase is shown in Fig.11, while the
seasonal variability is shown in Fig.12. It is remarkable that the anomalies as compared to the
1971-2009 period increase, and, in the last 15 years, there was only 1 year (1995) when the anomaly
was negative (though almost negligible). The seasonal picture is similar, with Spring and Summer
showing the largest temperature increase.
Precipitation anomalies are shown in Figure 13. The change is negative for almost the whole area of
the country, while the largest decrease in precipitation is experienced in the Lake Balaton
watershed. The most severe decrease is in the Zala river watershed (largest and dominant tributary
of Lake Balaton) with as much as 15 to 25 % decrease in the last 50 years.
These findings set the stage for the evaluation of climate change and climate impact in the Lake
Balaton Region.
15
Figure 10. Changes in the annual average temperatures in Hungary during the 1980 -2009 period
(Hungarian Meteorological Services, 2011)
Figure 11. Annual average temperature anomalies in Hungary between 1901 and 2009 as
compared to the average of the 1971- 2000 period. (Hungarian Meteorological Services, 2011)
16
Figure 12. Seasonal average temperature anomalies in Hungary between 1901
and 2009 as compared to the average of the 1971- 2000 period. (a) Spring, (b)
Summer, (c) Autumn, (d) Winter. (Hungarian Meteorological Services, 2011)
17
Figure 13. Changes in the annual precipitation in Hungary during the 1960 -2009 period
(Hungarian Meteorological Services, 2011)
3.2. Situation in the Lake Balaton region
3.2.1. Characteristics of the lake and it s catchment
Lake Balaton is large, extremely shallow lake with 588.5 km2 surface area and 3.36 m average
depth at the mean water level of 75 cm (zero point of the level gauge is 103.41 m above Baltic Sea
level), and 605 km2 surface area and 3.52 m average depth at 100 cm water level (Figure 14 shows
the bathimetry of the lake). Area of the lake changes little with increasing water level due to the
constructed (concrete) shoreline that occupies about 46 % of the total.
Extending to 3 counties in western Hungary, Lake Balaton catchment area is 5774.5 km2. The
largest subcatchment is that of Zala river in the West with an area of 2622 km2.
18
Figure 14. Bathimetric map of Lake Balaton (at 75 cm mean water level)
Figure 15. Lake Balaton catchment area with its tributaries
Drought is a main concern for Lake Balaton. The unprecedented drought from 2000 to 2003 resulted
in extreme low water level, loss of some 22 % of lake volume, and no outflow from the lake for
more than 5 years. Such a situation happened for the first time in the recorded history of the lake.
19
Another concern is the drop of groundwater level resulting in the sinking of ground and damage to
the built environment as well as the reduction of agricultural production. Additional impacts are the
increase of extreme weather events resulting in occasional flooding and erosion of the steep terrain
along the northern shore.
3.2.2. Documented effects of climate change in the catchment area
The extrordinary drought from 2000 to 2003 is demonstrated by the cumulative precipitation deficit
as shown in Fig.16.
Figure 16. Cummulative deficit of precipitation (mm) relative to the long term mean
during the 2000-2003 extreme drought period (Source: Kravinszkaja G, Pappné-Urbán J.,
Varga Gy.:Száraz és nedves időszakok hatása a Balaton 2000-2005 közötti vízháztartására,
2006)
20
In the watershed of the largest tributary of Lake Balaton (Zala river, representing some 55 % of
annual inflow on the long term), the precipitation deficit exceeded 700 mm, i.e. more than the
annual average precipitation of the region.
The multiannual low precipitation resulted in an even more severe reduction in the runoff from the
watershed.
Year
Table 1. Precipitation and runoff during and after the drought period (Varga, 2007)
Precipitation on the watershed
Inflow to the lake
as percenage of the long term multiannual average
2000
2001
2002
2003
2004
2005
2006
69
81
82
74
103
114
88
63
41
34
34
63
78
88
15228731
Figure 17. Long term annual runoff trend for Lake watershed (blue bars: annual precipitation
in mm, red line: 5-year moving average, black line: linear trend line)
21
The long term trend of runoff is negative, but fluctuation is very significant. The last 2 decades
show repeatedly low runoff values.
Precipitation to Lake Balaton shows similar trend with almost lmm/year decrease in the last 9
decades, resulting in some 90 mm decrease overall.
Figure 18. Long term annual precipitation trend for Lake Balaton (blue bars: annual precipitation
in mm, red line: 5-year moving average, black line: linear trend line)
As a result of the drought, the natural change of water balance, i.e. Precipitation + Inflow Evaporation became negative in year 2000 for the first time since reliable monitoring have been
introduced in 1921, and remained negative for three more years (Fig.19). Since water withdrawal
from the lake is insignificant (corresponds to some 30 mm annually) regulation of water use is not a
viable measure to prevent the dropping of the water level. Figure 20 shows the change of water level
in the drought years. The minimum level was 23 cm as opposed to the optimum 90 to 100 cm.
Consequences of low water level
Level drop for extended periods result in dried-up shoreline, formation of sand shelves, loss of
spawning area.
22
In addition, low levels inconvenience bathing tourists since they have to walk several hundred
meters to find water deep enough for swimming.
Low levels result in extreme shallow water where filamentous benthic algae (such as cladophora)
can grow in large masses. Wind action moves such algae mats to the shore or to the rip-rap, where
they decompose resulting in smell and aesthetic problems.
Figure 19. Annual Variation of the Natural Change of Water Resources (NCWR = Precipitation +
Inflow - Evaporation) for Lake Balaton.
23
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Figure 20. Seasonal change of water level (gauge) during and after the drought years (Thick blue
line: daily average water level, cm; thin blue line: lower control limit; thin red line: upper control
limit; thick red line: legal maximum level)
Water balance of the Lake is shown in the figure below. It can be observed that the long term
balance is positive, i.e. there is a considerable outflow from the lake, therefore salt content did not
build up, and there is an outflow of nutrients as well (10 to 20 t/year of TP). However, it is clear that
in recent decades the outflow decreased, and it was practically zero for the drought period from
2000 to 2003. The indicated 2 mm outflow is negligible and it was necessary to prevent anoxic and
odorous conditions in stagnant water of the outflowing Sio Canal in summer.
24
Inflow
Precipitation
Evaporation A B
ABC
ABC
C
900 850 400
618 600 500
920 950 980
YY\
VVV
Outflow
Water use
A
50
BC
50 50
A
B
C
610
500
2
Figure 21. Water balance of Lake Balaton in lake mm
A: long term average (1921-2003); B: average between1986-2003; C:
average between 2000-2003.
25
Figure 22. Excessive growth of filamentous algae Cladophora glomerata in extremely
shallow water (< 40 cm)
Due to the lack of outflow some 10 to 20 tons of phosphorus (i.e. some 10 to 15 % of total P load)
was not discharged from the lake - thereby worsening the nutrient situation.
The lack of outflow had two other serious adverse effects. One is the impossibility to catch eel
with eel-traps placed at the outflow sluice. In an average year the Balaton Fishing Company could
catch some 100 t of eel at very low cost (almost free). Since there was no outflow for 5 years, the
fishing company suffered huge losses. The other is the impossibility of the traffic of boats and
ships through the Sio canal connecting Lake Balaton and the Danube river.
Due to the low level, a considerable part of spawning surfaces and aqueous habitats dried up.
Figure 23 and 24 show the difference of water covered shore line at 0 cm and 120 cm water level.
At low water level, yachting and commercial shipping becomes difficult. Some larger ships and
yachts are stranded, load restrictions should be applied and harbours should be dredged
frequently.
At low water level, wind induced resuspension of the sediment is more effective resulting in
higher turbidity and potential problems of the feeding of zooplankton.
26
Surface area of water-covered substrate (m2)
0 cm vízállás esetén
:
.10000,0
--—
_
--
10000,1
20000,0
20000,1
30000,0
300001
40000,0
40000,1
50000,0
50000,1
60000,0
60000,1
70000,0
70000,1
80000,0
80000,1
90000,0
\
A
Figure 23. Distribution of estimated water covered shore surface area (potential substrate) at 0 cm
water level (Paulovits et al., 2007)
Surface area of water-covered substrate (m2)
120 cm vízállás esetén
0.0
0,1 10000.0
10000,1 -20000,0
—
20000,1 - 30000,0
—
30000,1 - 40000,0
—
40000,1 ■ 50000,0
50000,1 - 60000,0
60000,1 - 70000,0
------- 70000,1 - 80000,0
------- 30000,1 - 90000.0
X/
Figure 24. Distribution of estimated water covered shore surface area (potential substrate) at 120 cm
water level (Paulovits et al., 2007)
Dry weather also affects vineries and other agricultural production. During the experienced
extreme dry year from 2000 to 2003, vineries considered building water retaining facilities and
irrigation systems and applied soil cover by mulch-like materials to reduce evaporation.
27
Effects of high water level
Due to the increase of extreme weather, occasional increases of lake level due wind action as well
as seasonal high levels due to excessive precipitation are experienced. As a consequence of wind
action, level displacement of as much as 1 m was experienced causing damage to transportation
infrastructure. Winter high levels caused ice damage to the shoreline concrete structures
(beaches) as well as flooding of low-lying areas in the south-western end. Flooding threatens
houses close to the shoreline.
Effects of increased temperature
Németh et al. (2007) analyzed the thermal bioclimate and applied the physiologically equivalent
temperature (PET), the well-known and one of the most frequently used bioclimate index based
on the human energy balance models (Höppe, 1993, 1999, Matzarakis et al., 1999, VDI, 1998).
For calculating PET they used the RayMan model (Matzarakis et al., 2001, Matzarakis and Rutz,
2005). For the calculation they need to possess four meteorological parameters (air temperature,
relative humidity, wind speed and cloudiness) as well as some standard physiological parameters
(age, genus, bodyweight, height, average clothing and working). The daily PET series (at 12
UTC) were calculated for the period 1966-2006 (Some of the results are shown in Figure 25 and
26).
------YEAR ----------------- Linear trend (Year)
Figure 25. Mean annual PET for the town of Siofok, period 1966-2006
Figure 26. Variation of hot days at Siófok (Németh et al., 2007)
28
While the annual and seasonal means of PET are increasing, the number of comfortable days is on
the decrease. If these trends will continue in the next years, we should expect both positive and
negative results. The increasing demand for the waterside (beaches) as well as the increasing
length of the tourism season are the possible positive results. Negative impacts may be the
overcrowded beaches, the ecological problems resulting from the crowd, and the increasing
frequency of certain extreme weather events (heat waves, storms, droughts, vegetation fires, etc.).
These possible impacts mean that the tourism industry needs to draw up adaptation plans on
behalf of the sustainable tourism.
Figure 27: Mean daily temperature in the Zala catchment (1960-2002) (From Thacker, S.: Climate Change,
Water, and the Possible Impacts on Riverine Habitats: A Case Study for the Zala Catchment (Hungary),
Master Thesis, Potsdam Institute für Klimafolgenforschung, August, 2011)
4. Vulnerability to the effects of climate change - future scenarios
4.1. Hydrology and water quantity
In case of Lake Balaton alarming reports (in the media) appeared in 2002 and 2003, talking about
the shrinking or even the disappearance of Lake Balaton. Due to the potential impacts of extended
low level periods, Lake Balaton Development Council initiated studies about water transfer to the
lake from other watersheds. It has been proven that such water transfers are technically possible
(from at least 3 rivers) but the ecological impacts of such a step are largely unknown, just as the
extent of adverse economic impacts.
29
Novaky (2008) studied the impact of climate change on the water balance of Lake Balaton by
using IPCC emission scenarios and climate models. He found that increase in annual temperature
by 1.58 oC and decrease in annual precipitation by 5% are likely to lead to considerable decrease
in water recharge of lake. If an increase in annual temperature by 2.88 oC is coupled with a
decrease in precipitation by 10%, Lake Balaton could turn into a closed lake without outflow. It is
concluded that „despite the uncertanties involved, climate change will be a great challenge for
Lake Balaton"
Figure 28. The interval of variability of annual NWCR (red line) with 98% probability is
indicated for present and unchanged climate by the straight (blue lines) and for changed climate
by the broken (blue) lines. (Novaky, 2008)
30
Change of the relative frequency of daily average flows below 2 m3/s as well as 3 m3/s
(Zala river at Zalaapati)
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Years
Figure 29. Zala river extreme low flows
Change of the relative frequency of daily average flows over
10 m3/s as well as 20 m3/s
o
Ö
u&
£
15
tó
31
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Years
y = -0.0008 x + 1.6811
Figure 30. Zala river extreme high flows
32
Change of runoff
In figure 31, runoff from the catchment area of Lake Balaton is shown in 40 km2 cells for the
reference period of 1961-1990. A similar figure (Fig.32) has been constructed for the B2 climate
scenario, for 2025.
S
H
Runoff: mm |
0-25
25-50
51-75
76-100
101-125 |
126- |
Figure 31. Mean annual runoff in catchment of Lake Balaton for present climate (1961-1990).
(Novaky, 2008)
B2SRES. Had CM3. 2025
Runoff, mm
C-25
25-5C
51-75
7i-1 CO
101-125
Figure 32. Mean annual runoff in catchment of Lake Balaton for changed climate
33
(2025). (Novaky, 2008)
34
Table 2. Results of the modeling of Lake Balaton water balance (P+R-E is the Natural Change of Water Resources; Novaky, 2008.)
Period of years
Emission scenario
Climate model
Hutu,
Rim*
P + i?
E,itc
P■RE
1961-90
612
111
959
1,571
S74
697
2025
A2
HadCM3
594
82
709
1.303
948
355
ECHAM4
588
78
675
1,263
974
289
HadCM3
572
66
571
1,143
981
162
ECHAM4
594
79
683
1,277
978
299
A2
HadCM3
548
50
433
981
1,024
B2
HadCM3
565
55
476
1,039
1,023
B2
2050
<0
16
P&o precipitation over the lake; Ka^ui runoff from catchmcnts; s^ catch mens ru no ii converted to the lake's surfacc; evaporation from the lake's surfacc.
35
Month
----------1960-1979 ----------------------- 1980-2000 ----------------------- 2011-2030_Low .................... 2011-2030_Mid
----------201 l-2030_Higt l
2031-2050_Low
2031-2050_Mid
2031-2030_High
Figure 33: Discharge for the Zala Catchment STAR +2 Degree Rise (Monthly Averages) (Low,
Mid and High correspond to 10th, 50th and 90th rank of precipitations from 100 runs, with 2 oC
temperature forcing)
Figure 34. Changes in monthly average inflow to Lake Balaton Reference period
1970-1990. A2.B2 scenarios 2020-2040
120
0 -I ------- T ----- T ----- T ----- T ----- T ----- T ----- T ----- T ----- T ----- T ----1 2 3 4 5 6 7 S 9 10 11 12
Month
(Source: Kutics and Szalay, 2006)
36
Initiated by concern of low water level between 2000 and 2003, Honti and Somlyody (2005)
studied the necessity of water transfer as well as the probability of filling up of the lake to normal
level at present and under changed climate.
The changes considered until 2035 are as follows: Average temperature increases by 1.58C and
0.58C in the winter and summer respectively. This induces an increase in evaporation. Rainfall on
the whole watershed increases by 5% in winter and decreases by 15% in summer. This directly
appears in the precipitation falling onto the lake surface (P) and indirectly in the inflow (I). They
assumed a linear relationship between rainfall and runoff.
Figure 35. Lake Balaton and Rába River watersheds indicating the potential transfer
(Somlyody & Honti, 2005)
2003 2004
2005
2006
2003
37
2004
2005
2006
Figure 36. The effect of climate change on the restoration of lake level starting from December 2003.
Mean and 80% confidence interval from 1500 predictive simulations. Dots indicate observed water
levels in 2004 (Somlyody & Honti, 2005)
They concluded that water transfer is not necessary in the short run, but the events of extreme
drought may become more frequent, i.e. their probalility increases almost an order of magnitude
(from once in 100 year to once in a few decades). Their conclusion that the low level causes no
adverse changes in the ecological status is arguable (e.g. excessive benthic algae growth is
undesirable - refer to the photo) Another conclusion that keeping spring water level higher (and thus
storing water in the lake) is also subject to criticism since low laying areas are already in danger of
flooding at the present 110 cm maximum level. They emphasize the great deal of uncertanties
involved in prediction and decision making.
Figure 37. Annual minimum water level probabilities during the Monte-Carlo simulations with
the three climatic scenarios ("Present", Nova' ky and CLIME). White circles indicate the
corresponding probabilities derived from the 1921-2006 NCR database. All simulations utilized
the „0verflow1100" water level regulation strategy (i.e. keeping water level at maximum 110
cm when water is abundant) (Honti, M. and L. Somlyody: Stochastic water balance simulation for Lake
Balaton (Hungary) under climatic pressure Water Science & Technology 59, 3, 2009)
In yet another paper, Honti and Somlyody conducted a stochastic simulation study of the water
balance of Lake Balaton under climatic pressure. The comprehensive statistical analysis proved that
the water budget of Lake Balaton remains positive under all of the expected climatic scenarios, so
38
the lake will no dry out in the following decades. In this sense, there is no justification for artificial
water transfer. However, extremely low levels may occur during drought periods and the degree of
climate change will significantly alter the frequency of low levels in the future.
All the climate change studies on Lake Balaton point out the vulnerability of this extremely shallow
lake to climate changes and the great deal of uncertanties involved in climate scenarios and
modelling. In general, it can be concluded that the expected direction of climate change
(i.e.considerable warming and less precipitation) will have adverse effects on the water balance of
the lake, and requires adaptation steps to reduce these effects.
4.2. Lake water temperature
Lake water temperature is going to follow air temperaure changes, except in winter since no
negative water temperatures occur. The correlation between air and water temperatures is shown in
figure 38 for non-negative air temperatures.
Figure 38 Correlation of non-negative air and water temperature at Siofok basin lake centerline
(1977-2005
n=1033)
30
0
5
10 15 20 25 30 35 40
Air temperature. oC
The measurements were carried out from 1977 to 2005 in the middle of the Siófok basin. Air and
water temperatures were measured simultaneously in the framework of the regular water quality
monitoring process, in the morning hours. In beaches, water temperatures approaching 30 oC can
be measured in shallow waters but in the middle of the lake at about 4 m depth the temperature
values are lower.
39
4.3. Water quality
In case of Lake Balaton eutrophication and accompanying algae blooms constitute the challenge
of water quality control. Eutrophication started in the 1960s as a result of reckless nutrient
management in agriculture and the absence of appropriate sewage treatment. After the large scale
blooms of 1982, serious nutrient control measures were introduced and after a two decades water
quality seemed to stabilize. However, during the extreme drought period between 2000 and 2003
higher temperatures and low water levels resulted in less favourable water quality in terms of chl-a
(Figure 39)
Figure 39. Temporal and spatial change of annual maximum chla-concentrations in lake
Balaton.
The key nutrient responsible for eutrophication is phosphorus. The external total phosphorus (TP)
load was considerably reduced through sewer development and sewage treatment with P
precipitation, diversion of treated effluents to other watershed and the radical (though partly
unplanned) reduction of agricultural use of fertilizers. The lake responded to the TP control
measures with some delay, as it can be seen in figure 40.
40
Figure 40. Change of TP load and Chl-a concentration in the most eutrophic basin of Lake
Balaton
Change of complex water quality of the most important tributaries is shown in figure XYX. The
complex water quality indicator (5 is worse, 1 is best) is calculated from the concentration of
nutrients (P, N), BOD5, COD, Chl-a and suspended solids (SS) . The general trend is that the water
quality slowly improves since the mid 1980s.
Chl-a concentration has stabilized after the mntioned drought period, and it is generally acceptable
in all four basins of Lake Balaton (Figure 41).
Water level is an important factor in determining algae concentration in the lake. Vörös
41
studied the relation of themass blooms of benthic filamentous algae Cladophora glomerata and water
level. He found that below 50 cm level, large masses of the algae can be expected. The 50 cm level
means that at some parts of the lake (especially along the shallow southern shore) the effective water
depth is reduced to a few 10s of cm. Cl. glomerata has high light radiation tolerance (including UV)
and proliferates in the shallows. Wind action moves the algae mat from the bottom to the rip-rap
along the shores resulting in an unpleasant view and occasional smell. Kutics (2008) determined a
logistic curve to qunatitatively describe the relation between Cl. glomerata mass and water level.
3.5 3
2.5
£ 2 ra
tM.5
£ rz
51
T—r—T—i—i—T—T—1—i—r—T—T—r—1—i—1—t—T—i—r—r—i—T—1—i—T—T—T—r—i—
r—1—i—T—I—~i—T
-•— Fenek puszta Z a l a ' Z a l a a p a t i
Egerviz —■—Ny
jgati Övcsatorna —»—Tapolca patak
0.5 0
C O <
C □ o CJ -r
O
N
O O
f
fc tU
C <0 e0
5
O
o O) cr
O C
cn
>
>
) F
>
C D o <\ -a
O O
i O oo cn
O
O
l
(?)
C O) m
J>
( C o
O O
Ol O Ö
i
pi (?> o
**
O
C
J
D
o Q o
Q o
o
< C r> C
M J j
1
Year
Figure 41. Water quality indicator for the most impoerant tributarioes of Lake Balaton
42
Figure 43 Relationship between Cladopliora biomass and
water level in Lake Balaton (after Voros L , 2007) ,45 ! -----
5
(So
0
,
-
20 40 60 SO 100 120
OKIR, KDT KTVF Database)
Water level (H). cm
The relation between water level and phytoplankton chl-a is shown in figure 44. As it can be seen,
higher water level results in less algae, most probably due to more light limitation.
43
Figure 44. Water level vs. phytoplankton Chl-a concentration
Kutics et al. (2008) studied the effect of water temperature increase on expected annual peak
chl-a concentration through a P cycle model developed by Wake et al. (JICA, 1997, 2003) and
modified by Kutics and Szalay (2006). Two local climate scenarios corresponding roughly to the
IPCCs B2 and A2 scenarios were tested with external P loads kept unchanged . The results are
shown in figure 45. Simulations show that both scenarios result in water quality deterioration,
with BALALONE (A2) resulting in as high as 35% increase in chl-a level in the cleanest (Siófok)
basin of the lake. These finding indicate the importance of further reduction of external P load to
the lake.
44
Figure 45. Effect of climat e change on summer peak chl-a concentration (simulation)
4.4. Reed belt and peat bogs
The reed belt behaviour was studied by Herodek et al. recently in light of the extreme drought
period. It was found that water level change assists the advance of reed towards the open water,
which can be attributed to the possibility of proliferation through seeds as well as the reduced wave
action (less mechanical stress). It can be seen in figure 46 that the reed front moves when water level
is low or variable, and receeds when the water level is fixed at high value. One would state that low
water level is favourable, but from other aspects the low level poses threat to reed itself due to the
increased risk of reed fires that are difficult to control due to the slow and difficult accessibility
(mostly from boat).
On the other hand, low water level results in less habitat and spawning area for fish and other fauna.
45
Figure 46. Movement of reed front at different time intervals (water level was variable
between 1952 and 1982, mostly constantly high (controlled) from 1983 to 1999, and
low between 2000 and 2003). (Source: Herodek S.: A Balaton vízszintváltozásának hatásai a tó ökológiai
állapotára, Balatoni Partnerségi Program, Csopak, 2007. március 13.)
There are extensive peat bog areas around Lake Balaton since in the past the lake extended to as
much as 900 km2 area, with vast marshlands that connected to the lake (Figure 47). These peat bogs
are especially vulnerable to dry weather and low water level. In the dry year of 2003 some 250 ha of
peat burned out south of the lake and near the shore line. People had to be evacuated in the vicinity of
the town of Fonyód, traffic on main roads was stopped due to extensive smoke and extingusing the
fire would take several weeks and much human and other resources. Since peat mining is still going
on at some places, the market value of the burned peat can be estimated at 10 billion HUF. Reed and
peat fires are generally interconnected and can be caused by negligence, focused sun heat or
lightning.
46
Figure 47. Marshlands (pink circles) that are still functioning or became peat bogs
4.5. Fish and other macrofauna
Lake Balaton, as the largest freshwater lake in Central/Eastern Europe, is a critical site for
migratory species. Ducks Anas platyrhynchos, A. clypeata, A. penelope, Aythya ferina, A.
marila, A. fuligula , Bucephala clangula, Melanitta fusca and Mergellus albellus, geese Anser
anser and A. fabalis, swan Cygnus olor, coot Fulica atra, and diver Gavia arctica, use the site as a
staging area, and over 1% of the global Anser fabalis population can be found on the lake. Among
endangered resident species, the black stork (Ciconia nigra) and black woodpecker (Dryocopus
martius) are prominent. Some other ecologically important protected species include Egretta
alba, protected since 1922, E. garzetta, Ardea purpurea, Ciconia nigra, and Grus grus. The lake
itself contains about 2000 species of algae, 1200 species of invertebrates and 51 species of fish.
The flora and fauna of the surrounding landscape are particularly diverse due to the mild,
Mediterranean-like climate. A large number of rare and protected plant species can be found in
the area, including several rare, sub-mediterranean plant species, such as Sternbergia
colchiciflora and Scilla autumnalis on grasslands surrounding the lake. The area is especially rich
in insects: over 1,000 species have been identified. About 800 species of butterflies occur, some
of them are extremely rare, such as the ruby tiger (Phragmatobia fuliginosa) and the red
underwing (Spialia sertorius). The Kis Balaton, as a huge wetland habitat is unique in the whole
of Europe, which is why it has always been recorded by international nature conservation. In
recognition of its importance for
47
biodiversity, Lake Balaton has been designated a seasonal Ramsar site between October 1 and April
30 each year, while the adjoining Kis-Balaton, a reconstructed wetland and water pollution control
structure in the westernmost end of the lake received year-round designation and protection (Ramsar
Convention 2003a, Ramsar Convention 2003b). The Uplands Balaton several basins, (Pecsely
basin, Kali basin, Tapolca basin), representing unique ecosystems. According to the national red
data book around 30 important plant species are currently or potentially endangered and fall under
the protection and / or strict protection regimes
Commercial fish catch in Lake Balaton is declining since the end of the 1950s. (The increase
experienced in the first half of the 20th century is due to the improvement of fishing equipment and
enlargement of the operations - Figure 48.) The declining catch may be attributed to the loss of
spawning area due to the developement of shoreline protection concrete and stone structures (Figure
49). Although, probably it is not the only factor, it has been recognized that constructed shoreline
structures increase the vulnerability of the lake ecosystem, and no more such construction was done
in the last decade.
rSb Aqfbq<bc&oSb £>
A/ft/ft
A rS>
Figure 48. Five year average fish catch from Lake Balaton (Bercsényi, 2005)
48
Relation between the length of constructed (concrete) shoreline and
annual fish catch (1970-2000)
1600
1400 &
(Source: LB Fishing Co.., Pannon University: Dr. Bercsényi Miklós)
1200
o
o
E
y = -18.86x +2,693.59 R2
=0.78
^1000
800 600
■ - (Total shoreline length: 235.6 km)
400 200
0
65
115
75
85
95
105
Lenght of constructed shoreline, km
Figure 49. Constructed shoreline vs. annual fish catch
4.6. Invasive species
4.6.1 Plants
Perhaps most important invasive plants are ragweed (Ambrosia artemisiifolia) and goldenrod (
(Solidago canadensis scabra ), as well as tropical, nitrogen fixing blue-green algae
(Cylindrospermopsis raciborskii).
During mass algae blooms in the past (e.g. in 1982, 1992, 1994), C. raciborskii was the dominant
algae species. It constitutes risks due to potential toxin production.
Ragweed causes problems due to competition to agricultural products (e.g. sunflower) and due to its
highly allegenic nature. Unfortunately, historically the most ragweed-infected area is the Lake
Balaton region (Figure 50).
49
1922-1926
1927-1945
Figure 50. Historical advance of ragweed in Hungary (Source: Priszter 1957 1960, Béres Hunyadi 1991).
Recent situation of ragweed pollution is shown in Figure 51. We can see, that in most of the
watershed, ragweed constitutes a moderately serious to serious problem.
50
Figure 51. Incidence of ragweed in 2003 in the Lake Balaton
Watershed Green:0-1%, yellow: 2-10%, orange: 11-25%, red:
over 25% (Source: Hungarian Soil and Plant Protection
Services)
It is expected that ragweed would become more competitive with climate change therefore
serious control measures should be introduced.
4.6.2. Animals
Zebra mussel (Dreissena polymorpha) and a Ponto-Caspian amphipod (Corophium
curvispinum) were introduced to Lake Balaton by chance, through a barge from the Danube.
Both are invasive species; very good filters of phytoplankton. D. polymorpha causes trouble by
sticking to water withdrawal equipment, boats, piers, etc. Some oreign fish species were
introduced to Lake Balaton intentionally . Purpose: Fish production (eel), eutrophication
„control" (silver carp, grass carp). Results: Massive kills of eel; Excessive dependence of the
fishing industry on eel catch/exports; Disturbances in the food web; aging population of silver
carp ("biological bomb"); Loss or decrease in the population of indigenous species (e.g. pike,
Esox lucius) . Eeel (Anguilla anguilla)is omnivorous and though no seedlings are introduced
since the 1991-1992 mass kills, there is still a considerable population in Lake Balaton. White
silver carp (Hypophthalmichthys moltrix) and spotted silver carp (Hypophthalmichthys nobilis)
are planktivorous. They grow up to 60 kg, has no natural enemies in Lake Balaton, and may die
because of age. Very difficult to catch, jumps over nets like dolphins. Grass carp
(Ctenopharyngodon idella) is herbivorous. Selective fishing for silver carp is an ongoing project.
It is expected that climate change would not reduce (or rather, increase) the population
of these species.
51
4.7. Land use and agriculture
The distribution of main land use categories is shown in Table 3. Lake Balaton catchment has
much less arable land than the national average, considerably more forests, vineyards and
orchards and, of course more surface water.
Table 3. Land use in the Lake Balaton catchment as compared to national figures
Hungary
Lake Balaton
Lake Balaton direct
Land use category
catchment (total)
catchment
km2
%
km2
%
km2
%
Built-up area
5589
6,0
334
5,8
184
5,8
Arable land
49002
52,7
1779
30,8
807
25,6
Vineyard, orchard
2118
2,3
265
4,6
193
6,1
Misc. Agricultural
3309
3,6
257
4,5
93
2,9
Pasture, meadow
11813
12,7
695
12,0
375
11,9
Forest
17960
19,3
1640
28,4
832
26,4
Marshland
1260
1,4
170
2,9
81
2,6
Surface water
1962
2,1
635
11,0
588
18,6
Total
93013
100
5775
100
3153
100
On Figure 52, CORINE land cover is shown. Most of the „plantation" category mean vineyard in
the Lake Balaton region. Arable land is almost negligible in the northern part of the watershed,
which is a stepp, hilly area with forests, meadows and vineyards.
A study conducted by Kohlhebet al. (2009) on the desirable changes in land use taking the
possible impacts of climate change into account resulted in the changed land use map shown in
Figure 53. The changes include the increase of the area of forests and pastures/meadows and the
extensive cultivation (i.e. less fertilizers and chemicals) of arable land. According to the proposed
changes, intensive agricultural land use becomes almost negligibel in the catchment area. The
proposed changes are in line with the qualitative picture, i.e. increase of forested and
pasture/meadow area would be useful both for mitigation of and adaptationto the impacts of
climate change.
52
Artif. Surface
Arable land
Pasture, meadow
Plantation Forest
Wetland Surface
water Other
Figure 52. Surface cover according to CORINE database. (Source: Szent
István University, Environment and Landscape Management Institute,2009)
Present forest
Proposed forrest
Present pasture
Proposed pasture
Extensive arable land
Intensive arable land
Figure 53. Proposed land use pattern under to alleviate the effects of climate change (Source:
Szent István University, Environment and Landscape Management Institute,2009)
Lake Balaton catchment area is highly vulnerable to erosion and surface movement of soil (e.g.
loess walls collaps from time to time). The erosion potential map of the catchment area is shown
in figure 54. The proposed land use changes would reduce vulnerability to erosion as well. This is
very important since the combinded effects of
53
the increase of the frequency of extreme weather events and the change of the seasonal distribution
of precipitation (less precipitation in the vegetation period) would increase the vulnerability.
Figure 54. Classification of sub-catchments of Lake Balaton Catchment
based on erosion potential Light pink: 0 to 20, pink: 20 to 40, red: over
40 tons/ha/year (Source: Máté, F.: Szabályozási alternatívák a diffúz
foszfor terhelés csökkentésére a Balaton vízgyűjtőjén, 3/024/2001
NKFP research project, Pannon University)
4.8. Hunting
The general tendency is that large game population is 2 to 10 times higher than desirable (depending
on species), while small game is at about 50% of the favourable figure. The latter is due to the the
high population of carnivores such as fox. It is unclear how climate change would influence
hunting. Expected reduction of yield in agricultural production may result in tighter control of
games and therefor reduction of the population of most damaging species such as wildboar and roe.
4.9. Tourism
With more than 5 million guest nights annually, tourism is the most important sector of the
economy in the Lake Balaton region. Therefore, the economy is vulnerable to
54
changes in environmental conditions, including climate change. Figure 55 shows the municipal
GDP (estimated by a methodology developed by Lőcsei and Németh, 2005) as a function of
registered guest nights. Unfortunately, many of the guest nights go unregistered for various reasons,
including tax evasion. The real figure, including guest nights spent by „weekend house" owners,
can be as high as 12 million/year.
Figure 55 Relation between guest nights and local GDP in the towns of
the Lake Balaton Priority Resort Area (1994-2004)
80
01
O
J
.
P
♦
0
♦
70
____A--.
0
♦
h
600
ffi
o
O
o
Ph
Q
p
o
♦
•A---
y = 2.22x +228.49
R- = 0.8264
50
0
40
0
30
0
50
100
150
200
250
Guest night/permanent resident/year
200
10 One would expect that there is a clear correlation between summer temperatures
0 0 and guest nights.However, Figure 56 and 57 shows no apparent correlation in the
period of analysis (1990 -2006). The effect of temperature is clear if number of
people entering the beaches is analyzed. On a representative beach (Balatonalmádi), a strong
correlation has been found, and an icrease of 1 oC in summer average water temperature result in
about 8 to 10 % increase in the number of people buying entrance tickets (Figure 58)
55
Figure 56. Guest nights vs. summer average air temperature in the Lake Balaton Resort Area
Figure 57. Guest nights vs. summer average water temperature in the Lake Balaton Resort Area
56
4.10. Infrastructure
4.10.1. Buildings
In the extreme dry period from 2000 to 2003 the ground water table decreased by more than 1 m
at some locations (e.g. near Kis-Balaton wetland). This resulted in the displacement of the
foundation of buildings due to the shrinking of the underlying soil (clay, etc.). Subsequent wet
weather and increase of ground water level resulted in some displacement again. The
consequence was the development of cracks in the foundations and walls of buildings. Since the
occurence of extreme periods is going to increase, buildings around lake Balaton become more
vulnerable to such damages.
Another type of vulnerability emerge from the the extreme weather events such as strong wind,
storms, lake level displacement, falling down of trees, etc.
4.10.2 Roads and other linar infrastructure
Highway No 7 runs along the southern shore of the lake, crossing the massive wetland
„Nagyberek". Large scale water level changes in this wetland may damage the highway
infrastructure. Extreme events increase the probability of erosion of unpaved or weakly paved
surfaces in steep urban areas.
Main sewer lines extend for about 40 km along the north-east shore of the lake, transferring raw
and treated sewage to the Balatonfuzfo sewage treatment plant. High temperatures would
aggrawate the already existing odour and corrosion problem of this infrastructure.
Low water level causes problems in the operation of marinas and the ferry boat services. In case
of extreme low level anticipated in the future, new docking infrastructure of ferries as well as
regular and costly dredging of marinas becomes necessary. In addition, srew damage of motor
boats of the Balaton Shipping Company would be more frequent.
5. Assessment of potential economic impacts
Lake hydrology and water quantity
Low water level between 2000 and 2003 caused quantifiable and non-quantifiable (or
difficult to quantify) economic damages. Kutics (2004) estimated the economic impacts
of low water level and the lack of outflow from the lake.
57
Commercial shipping: 1.0 to 2.0 million Euro/year
Commercial fishing: 0.5 to 0.7 million Euro/year
Dredging of harbors and bathing areas: 1.3- 1.6 million Euro/year
Clean-up of cladophora biomass from shallow waters: 0.1 to 0.2 million Euro/year
Reduction of entrance fee revenues of beaches: 0.5 million Euro/year
Halt of shipping in Sio Canal: ?
Ecological damages: ?
The total quantifiable damages can be estimated to be in the 3.4 to 5.0 million Euro/year.
Further potential damages that are difficult to quantify are
-
Decrease of the number of tourists (guest nights)
-
Yacht owners chose harbours at other lakes or the Adriatic due to the low level
-
Overall decrease of tourism related incomes (total such income is estimated at
1,300 million Euro/year)
-
Value reduction of homes and second houses due to the loss of popularity of Lake
Balaton region (total value of the houses is estimated at 8.6 billion Euro)
Water quality
In case of mass blooms, regular removal of Cladophora glomerata biomass at ca. 50 beaches 50 x 10,000 Euro = 0.5 millio euro
P load reduction measures : urban and agricultural runoff control - see at erosion control
Water temperature
Increased water temperature may result in unsuitability of Lake Balaton water as drinking water
resources. In such a case, karstic water resources should be developed. Reed belts and peat bogs
Reed belt and peat bog fires can potentially result in tens of million euros in losses due to the loss
of reed and peat as commodities as well as loss of habitat. Fish and other macrofauna
Costs of selective silver carp catch is in the order of 0.1 million euro annually. Eel can be
eliminated only if there is (more or less) constant outflow from the lake. Invasive Species
Amount of ragweed can only be reduced through national level action. Loss of agricultural
production as well as work hours due to allergic reactions can go up to millions of euros. Land use
and agriculture
Change of land use patterns, forestation, irrigation of arable land and change of vinegrape species
involve large sums in the order of 10 millon euros. Erosion control both agricultural and urban
would cost at least 100 million euro for the lake-side municipalities. Tourism
Tourism income in the region is in the order of 1 to 1.5 billion euros. If problems with water
quality, quantity or other environmental problems occur, a 10% decrease would result in 100
58
million euro in losses for the businesses and subsequently less tax revenues for the municipal
governments. Infrastructure
The total value of houses is about 8.6 billion euro. Any percentage of damage due to grounfd
water level changes or extreme events can be expessed in tens of millions of euros.
59
6. Summary of findings related to vulnerability
Receptors
Lake water
level
Water
temperature
Table 4. Qualitative Vulnerability Assessment for Lake Balaton (up to ca. 2040)
Current Stresses
Vulnerability Assessment
Projected Climate
Change Impacts
Adaptive Capacity
SensitVulnerability Existence of (semi)
ivity
quantitative
assessment
Precipitation deficits
Higher frequency of drought
periods
Flooding
Slightly higher frequency of
extreme events
Ice damage to shoreline
structures
Slightly higher frequency of
extreme events
Very
High
High
High
Peat fires at marshlands
adjacent to the Lake
More frequent peat fires due to low
water level and dry conditions
Temperature increase
Occasional algae blooms
High
High
60
Very high
Outflow control,
Water transfer, Water
resources management
at river basin level
Probability of drought,
water balance
Increase Sió canal and Very high
sluice discharge
capacity,
Increase Sió canal and Very high
sluice discharge
capacity
Control water level of High
marshlands
Reduction of external Medium
P load
Correlation eq. with air
temperature
Table 4. Qualitative Vulnerability Assessment for Lake Balaton (up to ca. 2040)
(continued)
Receptors
Current Stresses
Projected Climate
Vulnerability Assessment
Adaptive Capacity
Change Impacts
SensitVulnerExistence
of
(semi)
ivity
ability
quantitative assessment
Water quality Occasional algae blooms
More frequent algae blooms
High
Growth of benthic filamentous Increase in frequency and mass of Cl. Very
High
algae Cl. glomerata
glomerata
Appearance of algae toxins
Pathogens
Increased frequency and conc. of
algae toxins
Increased concentration and survival
rate
Medium
High
Flash floods
Increase of erosion and pollutant load High
Reed belt
Changes in reed area, damage
at extreme events
More damage at extreme events
Grasslands
Vineyards
Rare drought damage
Drought damage
More frequent drought damage
Low
More frequent drought damage, more High
pests
Agriculture
in general
Damage due to extreme events More frequent drought damage, heat
stress, erosion, new pests
High
Forestry
Damage due to extreme
events, new pests
Medium
Low
More frequent drought damage, heat
stress, pests
61
Reduction of external High
P load, Management of
Kis-Balaton
Reduction of external
P load, Mechanical
removal from beaches
High
Reduction of external Low
P load
Urban runoff control Medium
Swan population control
Land management,
Urban runoff control
Water level
management, reed
harvesting practices
None
Species selection,
good practices
High
Species selection,
good practices,
melioration
Species selection,
understorey
management
Medium
Low
Low
Low
Medium
Simulation model for
Chl-a and load scenarios
Equation to estimate chl-a
from lake level
Table 4. Qualitative Vulnerability Assessment for Lake Balaton (up to ca. 2040)
Receptors
Current Stresses
Projected Climate
Vulnerability Assessment
Change Impacts
Sensitivity Adaptive Capacity
Vulnerability
Invasive
species
Fishery
Tourism
Human
health
Competition with
indigenous species
Human health risks due to
allergens
Occasional drying out of
spawning areas
More favourable conditions for
propagation
More favourable conditions for
propagation
More frequent drying out of
spawning areas
Medium
High
Medium
Reduced possibility of eel
Even less possibility of eel
Medium
removal at outflow
removal
Influence of extreme weather More frequent occurrence of low water High
levels, heat days, less ice cover
Removal and control
efforts
Removal campaigns,
good agric. practices
Outflow control,
water transfer
Medium
Outflow control
Medium
Outflow control, water
transfer, attraction
development, ice rinks
Existence of (semi)
quantitative
assessment
Medium
Medium
High
Occasional water quality
problem
More frequent water quality problem High
Nutrient load reduction, Medium
algae removal
Heat days, allergens, algae
toxins
More heat days, spread of new Medium
allergens, higher level of algae toxins
Heat shelters, allergen Medium
control, reduction of
pollutant load, rising
public awareness
62
(continued)
Connection of
spawning substrate to
water level
Otflow -eel catch
relation
Table 4. Qualitative Vulnerability Assessment for Lake Balaton (up to ca. 2040)
Receptors
Current Stresses
Projected Climate
Vulnerability Assessment
Change Impacts
Sensitivity Adaptive Capacity
Vulnerability
Infrastructure
Increased erosion in built-up More erosion and pollution from High
area due to extreme events
built-up area
Damage to buildings due to
ground water level changes
More frequent and larger ground water High
level changes
Odour problem of sewer
pumping stations
More odor problems due to higher High
water temperature and less flow
Problem of ferry, boat and Increase of frequency of problems
marina use due to low water
level
High
Damages to infrastructure due More frequent physical damages to Medium
to extreme events (winds,
infrastructure and buildings
heavy rain, snow and ice)
63
Erosion control
measures, rain water
storage, treatment,
reuse
Rain water storage,
recharge, ground water
level control
Odour control
measures, switching
drinking water
resources from Lake to
karstic water
Modification of ferry
ports, dredging of
marinas, use of smaller
boats
Development of
disaster plans and
measures
Medium
High
Medium
Medium
Medium
(continued)
Existence of (semi)
quantitative
assessment
Literature
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